dm: Rename U_BOOT_DRIVER_ALIAS to DM_DRIVER_ALIAS

We use the U_BOOT_ prefix (i.e. U_BOOT_DRIVER) to declare a driver but
in every other case we just use DM_. Update the alias macros to use the
DM_ prefix.

We could perhaps rename U_BOOT_DRIVER() to DM_DRIVER(), but this macro
is widely used and there is at least some benefit to indicating it us a
U-Boot driver, particularly for code ported from Linux. So for now, let's
keep that name.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pinctrl/nxp/pinctrl-mxs.c b/drivers/pinctrl/nxp/pinctrl-mxs.c
index 5ada2ac..449a0aa 100644
--- a/drivers/pinctrl/nxp/pinctrl-mxs.c
+++ b/drivers/pinctrl/nxp/pinctrl-mxs.c
@@ -192,4 +192,4 @@
 	.ops = &mxs_pinctrl_ops,
 };
 
-U_BOOT_DRIVER_ALIAS(fsl_imx23_pinctrl, fsl_imx28_pinctrl)
+DM_DRIVER_ALIAS(fsl_imx23_pinctrl, fsl_imx28_pinctrl)